Accessibility Glossary
WCAG criteria, patterns, and standards — with interactive demos, detection methods, and audit data.
How WCAG grades conformance: Level A, AA, and AAA, plus the principles behind them. AA is the usual legal target.
Conformance & Claims
Conformance is per-page, not per-site. Level AA means all A + AA criteria pass on that page. Claims should specify version (2.2), level (AA), scope (pages/processes), and date. Partial conformance exists for third-party content you don't control.
POUR Principles
The four pillars organizing all WCAG criteria: Perceivable (can users sense it?), Operable (can they interact?), Understandable (can they comprehend?), Robust (does it work with assistive tech?). If any pillar fails, the content is inaccessible.
WCAG Level A
The minimum baseline — 31 success criteria addressing the most critical barriers. Includes alt text (1.1.1), keyboard access (2.1.1), page titles (2.4.2), and error identification (3.3.1). Level A alone is not sufficient for legal compliance. (WCAG 2.2 marks 4.1.1 Parsing as obsolete, so it is no longer counted.)
WCAG Level AA
The legal standard worldwide — 24 additional criteria (55 total with A). Includes color contrast (1.4.3), reflow (1.4.10), focus visible (2.4.7), and all 4 new WCAG 2.2 AA criteria. Target this level. Referenced by ADA, EAA, Section 508, and EN 301 549.
WCAG Level AAA
Enhanced accessibility — 31 additional criteria (86 total: 31 A + 24 AA + 31 AAA). Includes sign language for video (1.2.6), 7:1 contrast (1.4.6), 44×44px targets (2.5.5), and reading level (3.1.5). Aspirational, not achievable for all content. Cherry-pick criteria that benefit your audience.